1. Field of the Invention
The field of this invention is polypeptide autoantibody inhibitors and methods of use thereof.
2. Background
Multiple sclerosis (MS) is a chronic relapsing remitting disorder disease of the central nervous system that affects 350,000 Americans and, second to trauma, is the leading cause of disability among young adults. MS is an immune-mediated disorder characterized pathologically by perivenular white matter infiltrates comprised of macrophages and mononuclear cells (inflammation), and destruction of the myelin sheaths that insulate nerve fibers (demyelination).
Experimental allergic encephalomyelitis (EAE) in rodents has been the most widely employed model for testing of therapies for human MS. These traditional disease models for MS generally have promoted the concept that MS is a T-cell-mediated disorder. However, the autoantigens that serve as targets for the immune attack have not been identified and the molecular mechanisms implicated in myelin damage remain uncertain. While it is clear that CNS inflammation in EAE is initiated by autoagressive T-cells that recognize myelin antigens in the context of class II-MHC molecules, many of the models lack the early demyelinating component of the MS lesion. B-cell activation and antibody responses appear necessary for the full development of EAE and earlier studies on immune mediated demyelination using myelinated cultures of CNS tissue have implicated humoral factors as effector mechanisms. Thus, it is not surprising that rodent EAE has not been a robust predictor of efficacy in humans as fundamental differences in the clinical course, pathology, and immunologic response to myelin proteins distinguish rodent EAE from human MS.
Recently a novel MS-like illness in an outbred nonhuman primate, the common marmoset Callithrix jacchus, has been defined. The marmoset EAE has a prominent, MS-like early demyelinating component which requires the presence of myelin-specific autoantibodies, and has afforded an opportunity to understand the interactions between these antibodies and their target antigens on myelin. Characteristics of the model include: a. Mild clinical signs and a relapsing remitting course similar to MS; b. A primary demyelinating pathology with early gliosis indistinguishable from MS lesions (demyelinating plaques); c. Natural bone marrow chimerism permitting successful adoptive transfer of encephalitogenic (e.g. disease-inducing) T-cell clones and lines; d. Diversity of the encephalitogenic repertoire of T-cells reactive against the major myelin protein myelin basic protein (MBP); e. Different disease phenotypes resulting from immunization with different myelin constituents: in contrast to whole myelin, immunization with MBP produces a non-demyelinating form of EAE; f. Demonstration that demyelination is antibody-mediated but also requires an encephalitogenic T-cell response to facilitate autoantibody access to the nervous system; and, g. A key role of myelin oligodendrocyte glycoprotein (MOG) in plaque formation: adoptive transfer of anti-MOG antibody in non-demyelinating MBP-EAE reproduces fully developed MS-like pathology.
The highly immunogenic properties of MOG ( less than 0.05% of total myelin protein) may be related to its extracellular location on the outermost lamellae of the myelin sheath, where it is accessible to pathogenic antibody in the context of blood brain barrier disruption by encephalitogenic T-cells. The C. jacchus model permits precise identification of cellular and humoral immune responses that result in an MS-like lesion in a species with immune and nervous system genes that are 90-95% homologous to humans. The relevance of this model to human MS is emphasized by the recent finding of strong T-cell and antibody responses to MOG in MS patients.
Auto-antibodies against MOG have been shown to be present in demyelinating lesions in the brain of patients with multiple sclerosis (MS)and C. jacchus primates with MOO induced experimental allergic encephalomyelitis (EAE). Furthermore, anti-MOG antibodies have been demonstrated to be essential for the development of demyelinating lesions in C. jacchus EAE Additionally, it was shown, that ultrastructural features of demyelinating lesion are virtually indistinguishable between marmosets and humans MOG specific F[abxe2x80x2]2 fragments obtained by pepsin digestion of polyclonal anti-MOG antibodies from MOG immunized C. jacchus were previously shown to be able to counteract the development of demyelination in C. jacchus animals. See U.S. Ser. No. 09/384,036, now U.S. Pat. No. 6,333,033, and related PCT/US99/19546. However, no information is available to date on the molecular diversity, neither of pathogenic antibodies in C. jacchus EAE, nor of F[abxe2x80x2]2 fragments able to act as their antagonists.
The invention provides methods and compositions for inhibiting autoantibody binding in demyelinating disease. The compositions comprise immunoglobulin CDR3 sequences derived from combinatorial phage display libraries selected for high-affinity MOO binding MOG-specific CDR3 sequences include heavy chain CDR3 sequences selected from the group consisting of SEQ ID NOS:1, 3, 5, 7, 9 and 11 and light chain CDR3 sequence selected from the group consisting of SEQ ID NOS:2, 4, 6, 8, 10 and 12. In particular embodiments, the heavy chain CDR3 sequence is SEQ ID NO:1; the heavy chain is within a VH1 variable region subfamily domain or a VH3 variable region subfamily domain; the light chain CDR3 sequence is SEQ ID NO:2; and the light chain is within a VxcexaIII variable region subfamily domain or a VxcexaI variable region subfamily domain. In a particular embodiment, the polypeptide comprises both heavy chain CDR3 sequence selected from the group consisting of SEQ ID NOS:1, 3, 5, 7, 9 and 11 and a second light chain CDR3 sequence selected from the group consisting of SEQ ID NOS:2, 4, 6, 8, 10 and 12. The CDR3 sequences may be incorporated into a wide variety of polypeptides, so long as the requisite MOG binding is maintained. In a preferred embodiment, the polypeptide is an F(ab).
The invention provides pharmaceutical compositions comprising a polypeptide according to claim 1 and a pharmaceutically acceptable carrier and use of the subject compositions in methods for inhibiting MOG-antibody binding. In general, these methods comprise the step of contacting a mixture of a MOG and an antibody with a subject polypeptide, whereby the MOG-antibody binding is inhibited. In a particular application, the method is a method of inhibiting demyelination associated with the binding of an autoantibody to a myelin oligodendrocyte glycoprotein (MOG) polypeptide, comprising the step of administering to a marmoset or human host, subject to a pathogenic MOG polypeptide-polyclonal autoantibody binding, an effective amount of a composition comprising a subject polypeptide not having a functional Fc portion and sufficient to specifically bind the MOG polypeptide and competitively inhibit the binding of the autoantibody to the MOG polypeptide, whereby the demyelination is inhibited. In more specific embodiments, the administered composition further comprises a MOG tolerogenic T-cell epitope. The method may also be practices with a composition comprising a plurality of subject polypeptides, wherein each of the plurality of polypeptides specifically binds a different MOG eptiope.